/*
 * Copyright (c) 2005, The haXe Project Contributors
 * All rights reserved.
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE HAXE PROJECT CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE HAXE PROJECT CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 */

/**
	The utility Sugar classes provide additional Iterable manipulation routines
**/


/**
	The PhysTools class adds additional common physics utility functions.
**/


class PhysTools2D{
	
	public static function repelForce(	fromPoint:Point, toPoint:Point, 
													spring:Point, distance_length:Float, repel_force:Float):Point{
    var diffX = fromPoint.x - toPoint.x;
    if (diffX > distance_length){return;}
    var diffY = fromPoint.y - toPoint.y;
    if (diffY > distance_length){return;}
    var diffDist = Math.sqrt((diffX * diffX) + (diffY * diffY));

    // Move away from non-connected nodes that are too close 
    if (diffDist < distance_length){
      var tension = repel_force * distance_length/diffDist;
      spring.x += diffX/diffDist*tension;
      spring.y += diffY/diffDist*tension;
    }
	
	}

	public static function springForce(	fromPoint:Point,toPoint:Point, 
													spring:Point,distance_length:Float, spring_force:Float, bidirectional:Bool = true):Point{

	    var diffX = fromPoint.x - toPoint.x;
	    var diffY = fromPoint.y - toPoint.y;
	    var diffDist = Math.sqrt((diffX * diffX) + (diffY * diffY));


	    // "Move towards" this connected node if it is too far away.
	    if (diffDist > distance_length){
	      var tension = spring_force * (diffDist-distance_length);
	      spring.x -= diffX/diffDist * tension;
	      spring.y -= diffY/diffDist * tension;
	    }

	    // "move away" from this connected node that is too close
	    // note:  This part could be skipped in some implementations...
	    if (diffDist < distance_length && bidirectional){
	      var tension = spring_force * (distance_length-diffDist);
	      spring.x += diffX/diffDist * tension;
	      spring.y += diffY/diffDist * tension;
	    }

	  }
	
	
	
}
